As an industrial printing technician for several years I have watched the industries technologies grow and for the most part improve the quality of print and reduce the maintenance and cost per print. The most recent addition to the field has been the use of standard HP printer cartridges for product marking and outer case coding. This technology and most of its functionality has been developed in the printing industry on large webs and in the mailing industry to address information.
Control is the key
The disadvantage to this printing technology is there are too many things that need to align to achieve quality print. The current Trident and Zar print engines are a single row of multiple nozzles. With the HP style system the ink cartridge itself has 2 channels one beside the other and the second row of nozzles needs to print exactly over the first row of nozzles or a ghost or blurry print is created. This is much less obvious in text printing but can be a disaster when printing graphic images or barcodes. Most manufacturers have included the ability to turn off one set of nozzles 150 DPI vs. 300 DPI. The print with only one channel enabled is half the darkness and if a nozzle in the cartridge failed or becomes blocked a clear line will be present in the print.
The second alignment comes into play when more than 1/2 inch tall characters or barcodes need to be printed. This is achieved by stacking multiple cartridges next to each other in a progressively higher pattern. This requires the second print cartridges print information to be perfectly timed to align with the previous print and so on for each additional cartridge. Unlike a home inkjet printer where the paper feed is controlled and the print cartridge speed and position is controlled in a manufacturing environment the cartridge is stationary and the material printed on is moving.
The ink cartridge has little to no “throw distance” so the print head needs to be placed very close to the material being printed on. Again on a web application or a vacuum table this is easily achieved. On a conveyor however the box or case must be properly aligned to the print heads to achieve quality print. If the cases or boxes are not properly erected and filled to maintain a square profile they will often catch on the print head or drag when passing and being printed. Remember all that timing and alignment I mentioned above? The alignment of the print is only controlled by the timing of the print cartridges. If the material drags or changes speed that timing is lost and all those alignments fail. Encoders are designed to adjust for speed changes in the conveyance system but if the material speed does not exactly match the conveyance systems speed you loose!
It’s Clean, Easy, and there is No Maintenance
All three of these statements are true, the water based inks used in most of these print systems is much cleaner that the oil based inks used in the Trident and Zar technologies. No maintenance can be a double edged sword with these style printers. Where improper cleaning of a Trident, Zar, or Drop on Demand printer can cost thousands in repairs and requires adequate training the oil based inks do not dry so they remain ready to print. The HP cartridges need removed and capped when not in use and are easily replaced by any employee. This can potentially cause your ink costs to skyrocket if your staff finds it easier to quickly replace a cartridge rather that clean and purge the unit. Purging is a function that sprays ink from the nozzles in an attempt to clear minor blockages. Your home or office printer does this on a regular basis; these systems require you to do it manually Importance Of Industry within the software. A cartridge that should give you thousands of prints can easily be thrown in the trash and replaced after only a few hundred prints. Ten times the original expected cost. In a high volume application there are bulk ink systems available. Remember that each cartridge in a multiple level configuration requires a separate ink level. To high a level and the cartridge will leak, to low and it will starve and air will be sucked in through the nozzles. I have seen only one bulk ink system that works well. As you probably can guess it was developed and designed by HP and is limited to the inks they produce. Be absolutely sure that the cost savings of a bulk system exceeds the maintenance and frustration of a poorly designed system. Also remember the cost of bulk cartridges is higher than a single use cartridge but can be replaced and disposed of just as quickly.
Is this type system right for you?
If you are printing a single line of print less than ½ inch tall and less that 20 characters it is a perfect system for you. You won’t have the alignment issues with a multiple head system. Most other systems will be designed to print one to 3 inches of print so the cost will be higher for functionality you do not need. I limited the print to 20 characters since consistent speed while printing is easier to maintain with smaller length prints.
If you require a multiple cartridge system you will need to ensure you can provide the following.
If you require a multiple cartridge system you will need to ensure you can provide the following.
The material to be printed on needs to be square. Uneven or bulging cases will not be printed well. Skewed cases will bind and drag when crossing the print head and give fuzzy or ghost printing.
Conveyor systems must be smooth and steady. Since the print head is stationary and the material is in motion, the opposite of a home or office printer, absolute speed control is a must for these systems.
Presentation to the printer must be perpendicular and square to the head. With little to no ability to print across any air gap distance the material being printed needs to be as close as possible without dragging the print heads. This required the distance to remain the same top to bottom and as the material passes side to side.
This type of printing technology has been in use and proven to work well. We all have some sort of ink jet printer in our homes and offices. As far as I am aware they all print with the Lean Manufacturing Notes cartridge nozzle facing down. I have found there are several adverse conditions that arise when these cartridges are orientated to print on a horizontal rather than vertical plain.
I have has great success with this technology in very controlled environments like pharmaceuticals, cosmetics, and laboratories where the products and materials are contained during transport and are for the most part robotically controlled. Printing on a vertical plain has also increased the dependability of these systems.